Help - booking confirmation email formatting

help please!

nearly ready to go live and in final testing. We are using the booking email confirmation template which we have briefly customised. If I run a preview it shows perfectly well on an iPhone (mail app) but if you actually set the site live and do a test booking it only shows text and links to ‘view in browser’ if you cannot see the content. Then the whole email has a load of links at each section and just looks like spam! If you open it on other devices rather than through the apple mail app it’s fine.
Trouble is, cancellation templates etc all work absolutely fine so I cannot figure out why this is the exception which is frustrating as it’s actually the most important one.

Any advice would be much appreciated.
Thanks!